1. Field of the Invention
The present invention relates to a magnetic sensor.
2. Related Background Art
As magnetic sensors used in thin-film magnetic recording and reproducing heads and the like, magnetoresistive (M) devices have conventionally been known. In general, the MR devices cause a current to flow between a fixed magnetization layer and a free magnetization layer and thus attain high outputs. In the MR devices, however, domain wall movements due to spin torques given by the current and the like yield signals unnecessary for the magnetic sensors.
On the other hand, a spin accumulation (SA) magnetic sensor in which a free magnetization layer and a fixed magnetization layer are formed on the same horizontal surface (nonmagnetic conductive layer for accumulating spins) has been known (see, for example, Japanese Patent Application Laid-Open No. 2007-299467 and Japanese Patent Publication No. 4029772). When a spin accumulation magnetic sensor is used for a thin-film magnetic recording and reproducing head, for example, it is unnecessary for a current to flow through a free magnetization layer which senses external magnetic fields of a magnetic recording medium and the like. Hence, the spin accumulation magnetic sensor can detect a magnetic state as an output voltage by utilizing a spin current alone. Therefore, the spin accumulation magnetic sensor is less likely to observe unnecessary signals which are seen in the M devices.